<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">

    <title>Title</title>
    <style>
        #can{
            box-shadow: 1px 1px 5px 5px #ccc;
            position: absolute;
            top:50%;
            left:50%;
            transform: translate(-50%,-50%);
        }
    </style>
</head>
<body>
<canvas id="can" width="450px" height="450px"></canvas>
<script type="application/javascript" src="mevent.js"></script>
<script type="application/javascript" src="aaa.js"></script>
</body>
</html>